1. Field of the Invention
The present invention relates to a method of processing recycled waste paper, and more particularly, to a method of processing a mixture of different types of waste paper.
2. Description of the Related Art
A stock preparation system is used to prepare a fiber suspension for use within a paper-making machine. Typically, the stock preparation system receives a source of fiber, such as wood or recycled waste paper. The fiber source is then broken down into individual fibers and further processed such as by screening, cleaning, deinking and bleaching to prepare the fiber suspension with physical properties suitable for the manufacture of the fiber web.
Recycled waste paper includes both white fibers and brown fibers, depending upon the source of the recycled waste paper. For example, recycled waste paper with brown fibers may be in the form of old corrugated carton (OCC) and/or sack paper. Recycled waste paper with white fibers may be in the form of news print, magazine, printing paper and/or writing paper. The white fibers typically were processed to a greater extent relative to the brown fibers when previously used in the paper-making process. Accordingly, the white fibers have physical properties such as fiber length, adhesion properties, etc. which are different from the brown fibers. Given the different physical properties between white fibers and brown fibers, it may be desirable to process the white fibers separately from the brown fibers to manufacture a fiber suspension. A known technique is to separate waste paper made from white fibers from waste paper made from brown fibers prior to the stock preparation processing. However, separating and sorting the white fibers from the brown fibers is time consuming and expensive.
It is also known to merely mix the white fibers and brown fibers together and use the resultant fiber suspension for the production of a suitable fiber web. However, mixing the white fibers and brown fibers together limits the types of fiber webs which may be produced with the resultant fiber suspension, and may not be the best use of the different types of fibers within the recycled waste paper.
What is needed in the art is a method of processing recycled waste paper which does not require pre-sorting of waste paper having both white fibers and brown fibers, and provides improved flexibility in terms of different types of fiber suspensions which may be produced using the mixed waste paper.